氧化鋅量子點尺寸對能帶變化及電子-聲子交互作用之影響

Abstract

我們成功地利用溶膠-凝膠製造氧化鋅量子點，再利用改變溶液濃度、加熱速率以及反應時間等方法去控制氧化鋅量子點的尺寸大小。 室溫螢光及吸收光譜觀察到明顯的藍位移現象，並與effective mass model 的弱侷限效應計算的結果相符合。室溫螢光與吸收光譜譜峰之間距隨氧化鋅量子點的尺寸變小而變大的現象，也顯示氧化鋅量子點存在量子侷限效應。最後，我們由Raman光譜發現隨著氧化鋅量子點的尺寸變小而造成能量守恆的鬆弛及電子-聲子交互作用的能量變小的現象。

ZnO quantum dots were successfully synthesized by a simple sol-gel method. The average size of quantum dots can be tailored under several well-controlled methods which are solution concentration, heating rate and aging time. Size-dependent blue shifts of photoluminescence and absorption spectra reveal the quantum confinement effect. The band gap enlargement is in agreement with the theoretical calculation based on the weak confinement of effective mass model. Furthermore, we observed increase of the size-dependent Stokes shift of the photoluminescence peak relative to the absorption onset as the particle size decreases. Finally, we observed the results that energy conservation was relaxed and electron-phonon coupling energy was decreasing with decreasing quantum dots size by Raman spectra.